1. Field of the Invention
The present invention relates to a wash tank for efficiently washes, sterilizes and dries small molded parts made of rubber or plastic requiring a high degree of washing, for example, molded parts of various rubber stoppers or medical joints. The wash tank of the present invention is particularly effective in washing small molded parts such as a rubber stopper for a stopper used as a plug of a medicine phial for drug, liquid medicine or the like, a rubber part in a complicated shape having air vent holes such as a rubber stopper for fluid therapy, a plastic joint for a blood circuit or the like.
2. Related Art of the Invention
There have been known as generally performed conventional methods of washing small molded parts such as a rubber stopper for a medicine phial and the like, an agitation washing process where articles to be washed (hereinafter, referred to as washed objects) are only dipped in water, agitated and washed, a high pressure jet washing process where high pressure jet is blown, a pulsation washing process where washing is conducted by generating pulsation of air from a distributor having a double mesh structure (Japanese Patent Laid-open No. Sho 55-124580/1980), an ultrasonic wave washing process where washed objects are stored in an ultrasonic wave cleaner and washed by ultrasonic wave, or the like.
However, it is difficult to make flow a washing solution uniformly only by dipping washed objects in water or a liquid medicine and agitating them and therefore, there is a concern what wash specks are liable to cause, articles are damaged by a friction therebetween or exfoliated foreign objects are re-adhered to articles and a satisfactory washing effect has yet to achieve.
Further, even with a rubber stopper, when articles are provided with a complicated shape having air vents such as a rubber stopper for a half stopper or a rubber stopper for fluid therapy or the like, fine portions such as recessed portions or inner surfaces of small holes are difficult to wash. Even with the high pressure jet washing process, when a large amount of molded articles are washed in one operation, the jet stream is not made to blow uniformly to all of the articles and the uniform washing is difficult even with a single article since the degree of impingement of a jet stream is distributed and further, fine bubbles under the skin, a small amount of air adhered to a coarse surface or the like cannot be completely removed.
Furthermore, with respect to the ultrasonic wave washing process, when the washed object is an elastic article such as a rubber stopper, a sound wave is absorbed by the soft face whereby almost no washing effect is achieved. Also, with respect to the pulsation washing process utilizing the pulsation of air, a distributor for generating the pulsation of air is installed at a lower portion of a washer and therefore, when the specific weight of the washed object is small, the washed objects aggregate at upper portion of a washer whereby the washing effect is not sufficient and other washing system has to be used. As described above, it is the actual current situation that the satisfactory washing effect has not been achieved by any processes in washing various small molded articles made of rubber or plastic requiring a high degree of washability accordingly, a wash tank capable of efficiently washing objects by using a single tank and further capable of conducting sterilization and drying by using the same tank irrespective of a difference in materials of washed objects or magnitude of the specific weight has been desired. There have been various conventional rubber products the materials of which were brittle and where the rubber stopper per se was damaged by a jet stream and contamination frequently occurred. However, in recent times the rubber quality is improved and the jet stream washing becomes applicable. In view of the situation, the inventors have invented a washing device having a draft tube the upper end and the lower end of which are expanded for resolving the above-described problems and applied for a patent as Japanese Application No. Sho 57-229881/1982. According to the device, foreign objects are effectively exfoliated by circulating washed objects at the outside and the inside of the draft tube whereby the washed objects can uniformly be washed
One of the inventors invented a washing device where a cylindrical rotary drum is disposed in a sealed vessel to carry out further effective washing and applied for a patent as Japanese Application No. Sho 60-104736/1985. This device is a washing device having a cylindrical rotary drum in a sealed vessel which utilizes a jet stream generated in the rotary drum by a water jet pump.
However, the device described in Japanese Application No. Sho 57-229881/1982, has only the washing function and although the washing effect is significant when the specific weight of a washed object is large, a sufficient washing effect is not achieved when the specific weight is small. Meanwhile, with respect to the washing device described in Japanese Application No. Sho 60-104736/1985 sealing of rotary portions is indispensable since the rotary drum is disposed in the sealed vessel and the occurrence of foreign objects by dislodged abrasion of the rotating portions or invasion of foreign objects from a mechanical seal portion or the like is not totally dispensed with. Furthermore, as mentioned above, the device per se is complicated and the device is magnified whereby too much cost is imposed in manufacturing thereof. Accordingly, it is an object of the present invention to provide a highly practical wash tank of a compact type with no concern of occurrence or invasion of foreign objects where the washing effect is excellent irrespective of the magnitude of the specific weight of washed objects and the structure is simple and where also sterilization and drying can be conducted by using the same tank.